linux-kernel - [PATCH] opp: Allow opp-level to be set to 0

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Date:   Fri, 11 Sep 2020 15:19:53 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Stephan Gerhold <stephan@...hold.net>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] opp: Allow opp-level to be set to 0

The DT bindings don't put such a constraint, nor should the kernel. It
is perfectly fine for opp-level to be set to 0, if we need to put the
performance state votes for a domain for a particular OPP.

Reported-by: Stephan Gerhold <stephan@...hold.net>
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/opp/core.c |  3 ---
 drivers/opp/of.c   | 20 +++++++-------------
 2 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 214c1619b445..2483e765318a 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -2117,9 +2117,6 @@ int dev_pm_opp_xlate_performance_state(struct opp_table *src_table,
 	int dest_pstate = -EINVAL;
 	int i;
 
-	if (!pstate)
-		return 0;
-
 	/*
 	 * Normally the src_table will have the "required_opps" property set to
 	 * point to one of the OPPs in the dst_table, but in some cases the
diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index e72753be7dc7..87f839a1899a 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -842,7 +842,7 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
 static int _of_add_opp_table_v2(struct device *dev, struct opp_table *opp_table)
 {
 	struct device_node *np;
-	int ret, count = 0, pstate_count = 0;
+	int ret, count = 0;
 	struct dev_pm_opp *opp;
 
 	/* OPP table is already initialized for the device */
@@ -876,20 +876,14 @@ static int _of_add_opp_table_v2(struct device *dev, struct opp_table *opp_table)
 		goto remove_static_opp;
 	}
 
-	list_for_each_entry(opp, &opp_table->opp_list, node)
-		pstate_count += !!opp->pstate;
-
-	/* Either all or none of the nodes shall have performance state set */
-	if (pstate_count && pstate_count != count) {
-		dev_err(dev, "Not all nodes have performance state set (%d: %d)\n",
-			count, pstate_count);
-		ret = -ENOENT;
-		goto remove_static_opp;
+	list_for_each_entry(opp, &opp_table->opp_list, node) {
+		/* Any non-zero performance state would enable the feature */
+		if (opp->pstate) {
+			opp_table->genpd_performance_state = true;
+			break;
+		}
 	}
 
-	if (pstate_count)
-		opp_table->genpd_performance_state = true;
-
 	return 0;
 
 remove_static_opp:
-- 
2.25.0.rc1.19.g042ed3e048af